It is widely known that climate change has resulted in prolonged infestations of mountain pine beetle in the mountain states of North America, which has destroyed wide areas of lodgepole pine forest. Previously, cold spells had killed off bark beetles which are now attacking the forests.

The following story from the ABC suggests that climate change may be having a similar impact on the Monaro Tablelands of south eastern NSW.

For more than a decade it has been a mystery as to what is causing eucalypt trees to die on the Monaro in south-east, New South Wales.

The dieback is centred around Berridale near Cooma NSW and it spans more than 2000 square kilometres – an area larger than the ACT.

Research by PhD candidate Catherine Ross, from the Australian National University, suggests that climate change has played a role in the spread of the weevils and the stress on the ribbon gum trees.

“The weevils are native to the region and are found right across south eastern Australia, so the question was, ‘Why is it only affecting the Monaro?'” she said.

While agricultural practices have caused dieback in other parts of Australia, there was no evidence that it was a factor on the Monaro Plains.

“If it was agricultural practices, as I assumed, that would indicate that it was putting the trees under more stress, which was making them more susceptible to attack by insects,” she said.

“Or it could be that there was a predator or a parasite that was missing from the landscape, but none of those things seemed to fit in this case, because there was a lack of difference between reserves and grazed areas.”

“So what I’ve come to the conclusion is the underlying cause – is that it has something to do with the climate in the Monaro, which is already very harsh and variable.

“The region is in a rain shadow of the Snowy Mountains so it has low rainfall in comparison to the surrounding areas.

“It also has extremes of heat and cold which make it difficult for plants to grow. But over the last few decades, and in particular due to the Millennium Drought, there’s been a severe reduction of rainfall particularly in the autumn, which is a particularly important growth period for plants.”

While it’s not clear what the exact relationship is between climate change and the insect attack, Ms Ross said the dieback had a severe impact on local biodiversity.